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A compiler is provided to generate C++ code for the constraints and
the update rules. First, the syntax of the language that is used to
describe the constraints and the update rules is described. Second,
the generated code is determined.
Using a compiler instead of generic on-line
evaluator for the constraints and the update rules has the following
advantages:
- All constraints are saved in one text file (likewise the
update rules). This makes the data entry very easy. We can add,
update, and delete any constraint or update rule using any text
editor.
- Complicated data structures are not required for evaluation.
- The database is very simple, which facilitates maintaining the
design history.
- Format changes, or changes in the generated
code require only changes to the compiler, and no changes in the
system are required.
On the other hand, it has the following disadvantages:
- The generated code has to be included in the system and
the whole system must be recompiled.
- A compiler needs to be implemented.
Notice that the changes in the constraints or the update rules are not
frequent, so recompiling the system is not a big problem. Also, the
syntax used is very simple; therefore the compiler for such language
is not difficult to implement.
Matanya Elchanani
Wed Dec 18 17:00:21 EST 1996